PANDEMIC INFLUENZA: NON-PHARMACEUTICAL PANDEMIC INFLUENZA: NON-PHARMACEUTICAL INTERVENTIONS AND BEHAVIORAL

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  • PANDEMIC INFLUENZA:

    NON-PHARMACEUTICAL INTERVENTIONS AND BEHAVIORAL CHANGES

    THAT MAY SAVE LIVES

    Stan Finkelstein1, Shiva Prakash1, Karima Nigmatulina1,Tamar Klaiman2, Richard Larson1,3

    1Engineering Systems Division, Massachusetts Institute of Technology, Cambridge,

    Massachusetts 02139 USA 2O’Neill Center for National and Global Health Law, Georgetown University, 37th and O

    Streets, NW, Washington, DC 20057 USA KEYWORDS Pandemic, Influenza, Public Health, Social Distancing, Non-Pharmaceutical Interventions ACKNOWLEGEMENTS Work on this manuscript was supported by the Sloan Foundation of New York under a grant entitled, "Decision-Oriented Analysis of Pandemic Flu Preparedness & Response," and under a cooperative agreement with the U.S. Centers for Disease Control and Prevention (CDC), grant number 1 PO1 TP000307-01, "LAMPS (Linking Assessment and Measurement to Performance in PHEP Systems), awarded to the Harvard School of Public Health Center for Public Health Preparedness (HSPHCPHP) and the Massachusetts Institute of Technology (MIT), Center for Engineering Systems Fundamentals (CESF). The discussion and conclusions in this chapter are those of the authors and do not necessarily represent the views of the Sloan Foundation, the CDC, the U.S. Department of Health and Human Services, Harvard or MIT. We gratefully acknowledge the assistance of Marilyn Edobor, Alexander Flis, Stephen P Fournier and Katsunobu Sasanuma.

    3 Corresponding author 77 Massachusetts Ave. Building E40-233 Cambridge, MA 02139-4307 Phone: 617.253.3604 Email: rclarson@mit.edu

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    ABSTRACT The outbreak of novel A/H1N1 influenza in early 2009, eventually resulting in the declaration of a pandemic by the World Health Organization, raises the spectre of past pandemics and their devastating effects in terms both of economic consequences and, more important, human mortality. In the United States, individual states are responsible for pandemic influenza preparedness planning. A systematic review of state preparedness plans conducted prior to the 2009 outbreak reveals that a critical component of successful plans – namely, non- pharmaceutical interventions (NPIs) related to hygiene, social distancing, and technology – are incorporated to a far lesser degree than is necessary to ensure that the United States can successfully meet the challenge of pandemic influenza.

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    INTRODUCTION AND BACKGROUND

    In April 2009, cases of influenza caused by a strain of A/H1N1 virus that had not

    previously been seen in humans began to be reported in Mexico. The strain’s genome included

    material of swine, avian, and human origin and came to be referred to as the “swine flu.” By

    mid-June, this novel H1N1 had spread to more than 70 countries. By June 11, the World Health

    Organization declared a full-fledged pandemic.

    For several years prior to this 2009 event, concern by scientists and medical professionals

    the world over focused on the potential threat of a form of Influenza A virus subtype H5N1, also

    known as A(H5N1), which can cause illness in humans and many other animal species. Its bird-

    adapted strain – HPAI A(H5N1) – is familiar to most as “avian influenza” or “bird flu,” and has

    become endemic in many bird populations, particularly in Southeast Asia. Already, it has killed

    millions of birds and forced humans to slaughter and dispose of hundreds of millions of others to

    halt its proliferation. Another strain, Z+, is a growing killing machine among pigs, cats, and

    mice, and has mutated to become proficient in getting deep into human lung tissue and

    destroying it – with death a likely result. It has also been found to be a powerful weapon against

    the human central nervous system. Avian influenza A(H5N1) “is progressively adapting to

    mammals and becoming more neurologically virulent” (De Jong, 2005). As H5N1 in birds

    spreads across the globe, the threat of yet another pandemic heightens and accelerates. The strain

    mutates quickly, making it difficult for researchers developing medicines to keep pace. So, at

    present we are fighting one confirmed influenza pandemic and face the threat of another much

    more dangerous one.

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    The pressing question is whether history will repeat. In the Christmas 1918 edition, the

    editors of the Journal of the American Medical Association published an ominous comment:

    “The year 1918 has gone: a year momentous as the termination of the most cruel war in the

    annals of the human race; a year which marked, the end at least for a time, of man’s destruction

    of man; unfortunately a year in which developed a most fatal infectious disease causing the death

    of hundreds of thousands of human beings. Medical science for four and one-half years devoted

    itself to putting men on the firing line and keeping them there. Now it must turn with its whole

    might to combating the greatest enemy of all – infectious disease.”

    The new enemy was pandemic influenza. Just as World War I was coming to a close,

    having cost the world 20 million deaths and 21 million wounded (both military and civilian),

    something far more deadly was emerging. The influenza pandemic of 1918-1919 knew no

    borders, and no army could be mustered against it in battle. Its brutal reach was far greater than

    that of the war: upwards of one-third of the world’s population was infected (as many as 500

    million people), and the death toll reached nearly 50 million. Hardest hit were people ages 20 to

    40, contradicting the history of the disease, which had always primarily killed young children

    and the elderly.

    While our collective consciousness “remembers” the Black Death or Bubonic Plague of

    1347-1351, the pandemic of less than a century ago killed more people in a single year. It is

    likely the most devastating pandemic in recorded human history. A few more of the staggering

    statistics from that period are worth repeating.

    · About 28 percent of all Americans were infected (Tice, 1997).

    · The average lifespan in the United States was diminished by 10 years.

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    · The mortality rate was 2.5 percent, compared with less than 0.1 percent in previous

    epidemics (Taubenberger et al., 1997).

    Why do we speak of those events with such urgency? The statistics will likely pale in

    comparison to what might occur today, if we are not prepared. The alarm now sounds for the

    potential effects of pandemic influenza in a world with a far larger and often more densely

    concentrated urban population and in which the ease of travel, and hence human-to-human

    contact, makes 1918-1919 look like a prehistoric era.

    Faced with even the possibility of any sort of viral pandemic, most attention is typically

    paid to medical interventions, including vaccines and anti-viral medications. Vaccines and drugs,

    which take time to discover and produce, are little match for pandemic influenza if the objective

    is to slow the spread of the sickness.

    Considerable experience has been gained in developing vaccines for a seasonal outbreak

    of influenza. A vaccine is only useful if it corresponds to the strain of influenza by which we

    come under attack. No one can predict with perfect accuracy the strain we will be fighting

    because viruses constantly mutate. Thus, we cannot count completely on any of the coming

    vaccines being exactly what we need. The technical solution of vaccines, available before the

    influenza hits, involves guesswork. By the time the dominant strain has been fully characterized,

    it is already producing human cases. And it will take, typically four to six months to manufacture

    it, and even longer before it can be distributed to those at risk. If the experts guess incorrectly,

    the population gets little protection from the vaccine. When the threat is an impending flu

    pandemic and the viral culprit had not been seen before, the vaccine will first become available

    late in the progression of the disease.

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    There is a role for anti-viral drugs in treating novel influenza, as long as the flu strain is

    not resistant to them. Even if adequate supplies of these medications are available, the logistics

    of distributing them are complex. And the very short time window within which symptomatic

    individuals must ingest these medicines in order to receive benefit will greatly limit their value in

    preventing spread of the disease throughout the population.

    There are, however, other critical steps that can be taken that are powerful, effective,

    relatively inexpensive, and do not correspond to gambling on vaccines and drugs. These non-

    pharmaceutical interventions (NPIs) involve either hygiene or social distancing measures. Since

    influenza is transmitted through the respiratory emissions of ill individuals when they cough,

    sneeze, or talk, there is widespread agreement that hygiene measures such as proper hand

    washing, wearing of masks, and particular ways of covering the mouth when coughing or

    sneezing can be effective ways to reduce the spread and severity of a pandemic. Social